Reviews in Fish Biology and Fisheries

The analysis of elements in calcifiedstructures of fish (e.g., otoliths) todiscriminate among fish stocks and determineconnectivity between populations is becomingwidespread in fisheries research. Recently, theconcentrations of elements in otoliths arebeing analysed on finer scales that allow thedetermination of a continuous record of otolithchemistry over a fish's entire life history.These elemental concentrations can potentiallybe used to reconstruct migration patterns,based upon the influence that water chemistry,temperature, and salinity have on otolithchemistry. In doing so, assumptions are madeabout how environmental and biological factorsinfluence the concentration of elements in fishotoliths. However, there have been fewexperiments that have tested crucialassumptions regarding what influences elementaluptake and incorporation into fish otoliths.Specifically, knowledge regarding interactionsamong environmental variables, such as theambient concentration of elements in water,temperature, and salinity, and how they mayaffect otolith chemistry, is limited.Similarly, our understanding of the rate atwhich elements are incorporated into otolithsand the implications this may have forinterpretations is lacking. This reviewdiscusses methods of determining movement offish, the development of otolith research, andsome physiological aspects of otoliths (e.g.,pathways of elemental uptake). The types ofanalysis techniques that will lead to reliableand accurate migratory reconstructions areoutlined. The effects that have on otolith chemistry arereviewed with the specific aim of highlightingareas lacking environmentalvariables in experimental data. Theinfluences of the rate of elementalincorporation and ontogeny on otolith chemistryare also addressed. Finally, future researchdirections are suggested that will fill thegaps in our current knowledge of otolithchemistry. Hypotheses that need to be tested inorder to reconstruct the migratory histories offish are outlined, in a bid to clarify thedirection that research should take beforecomplex reconstructions are attempted.

Argentina is among the 20 largest seafood producing countries in the world, with an annual fish capture of about 800,000 tons. However, national annual fish consumption is low, about 5 kg per capita, and the domestic seafood market is little known. The objective of this study was to contribute to the characterization of seafood in the Argentine market. Monthly landings, presence at points of sale and prices of seafood were analyzed. The seafood data were gathered from official statistics of the Undersecretariat of Fisheries and Aquaculture, statistics from the Central Market of Buenos Aires and surveys conducted in fish shops in the city of Mar del Plata. Based on the monthly seasonal index (SI), price variations throughout the year were studied. Likewise, relative fish prices were determined by using as unit the price of Argentine hake (Merluccius hubbsi), which is the most consumed fish in the country. This study identified the marine species most present in the domestic market and their prices. The presence of the different fish species at the points of sale could not be directly associated with their landing seasons. There was also no direct link between fish prices and quantities landed. No significant seasonal fluctuations in prices were found on seafood products (SI = 90–110), with the exception of hake fillet (SI = 80–113). Many finfishes had a price peak during Easter week. Overall, price patterns suggest that seafood prices in Argentina are mainly determined by demand rather than supply. Further research on seafood traceability and fish consumption is needed to advance the understanding of the seafood market in Argentina.

We examined how human harvesting impacts on managed areas affect the abundance and size distribution of the edible mangrove shellfish Anadara granosa and Polymesoda spp. in the Roviana Lagoon, Solomon Islands. We tested two hypotheses: (1) in areas permanently and temporally closed to human exploitation, abundance and size distribution of these shellfish species is significantly greater than in sites open to exploitation and (2) moderate human disturbance of shell beds, particularly of Polymesoda spp., increases their abundance. Firstly, we studied perceptions of environmental states and processes coupled to foraging and management interventions to assess sociocultural influences on harvesting practices and ascertain the types of management regime that people would consider in a context where poaching and interloping are common practices. Secondly, we compared shellfish abundance and shell size from areas that were permanently protected, temporally reserved for communal harvest, and permanently open for exploitation. Thirdly, drawing from women’s local knowledge, we measured the abundance of Polymesoda spp. in relation to mud compactness in quadrats across the three management regimes. Results showed that both species were significantly more abundant in permanent and temporally closed sites than in open sites. In the mud compactness study, however, while shell abundance was greater in moderately compacted quadrats, there was no statistical relationship between mud compactness and shell abundance within or across the three management regimes. Results suggest that even under the strong impacts of poaching, temporally closed areas have more clams than open areas and are as effective as areas that are permanently closed nominally. The results also suggest that human harvesting regimes can influence the effectiveness of local management decisions and thus are important when designing community-based conservation programs in the Solomon Islands and other Pacific Islands.

Twenty leading scientists in the field of marine conservation planning attended the first international workshop on conservation planning in the Mediterranean Sea. This globally significant biodiversity hotspot has been subjected to human exploitation and degradation for 1,000s of years. Recently, several initiatives have tried to identify priority areas for conservation across the Mediterranean Sea. However, none of these efforts have led to large-scale actions yet. The aim of the workshop was to establish a network of scientists who are involved in large-scale conservation planning initiatives throughout the Mediterranean basin to promote collaboration and reduce redundancy in conservation initiatives. The three focus groups of the workshop build on existing efforts and intend to deliver: (1) a roadmap for setting conservation priorities, (2) a methodological framework for linking threats, actions and costs to improve the prioritization process, and (3) a systematic conservation planning process tailored to complex environments such as the Mediterranean Sea. Joining forces and involving more scientists (especially from the South-eastern part of the region) in following meetings, the participants endeavour to provide guidelines on how to bridge the science-policy gap and hence aid decision-makers to take efficient conservation actions.

The objective of the present study was to examine the effect of a wheat-gluten-based diet supplemented with the indispensable amino acid source in the form of free amino acid or dipeptide on growth, intestine oligopeptide transporter, PepT1, transcript levels using real-time RT-PCR, and muscle protein expression in yellow perch Perca flavescens juveniles. Yellow perch (initial size ~0.3 g) were randomly distributed into 12 glass aquaria, 60 fish per tank. Fish were fed 4 diets: wheat-gluten based diet supplemented with lysine–glycine dipeptide (LG), wheat-gluten based diet supplemented with free lysine (FL), diet not supplemented with lysine (NL; negative control) and a commercial diet (BO). Fish were fed at 90 % satiation level and the rate was re-adjusted to be equal across all treatments based on each day’s projected change in weight gain. It amounted to 3 % of the biomass per day for the first 14 days and 4–5 % until the end of the experiment. After 55 days of the experiment the mean weight of juvenile yellow perch fed the LG diet was larger compared to the NL diet fed group. There was no difference, however, between LG, FL, and BO groups (1.35 ± 0.11 g; 1.31 ± 0.03; 1.16 ± 0.10 g, respectively). Fish subjected to FL treatment showed an increase in the amount of PepT1 transcripts compared to the NL group value. The LG diet was associated with a significant increase in PepT1 mRNA transcript levels, compared with both FL and NL diets fed fish. We have also cloned and sequenced full-length cDNA representing yellow perch PepT1. The cDNA sequence (GeneBank: accession no. GQ906471), encompasses a total of 2,956 base pairs (bp) including a 5′-untranslated region of 94 bp, an open reading frame of 2,190 bp, and a 3′-untranslated region of 672 bp. The predicted 12 transmembrane domains and the 3D structure of the protein (729 amino acids) are presented. Proteomic fingerprinting showed that thirteen electrophoretically resolved protein/peptide bands from the muscle sarcoplasmic fraction were significantly different across treatments suggesting that muscle protein expression was influenced by dietary treatments.

I review the role of environmental variability in the survival of juvenile fish and shellfish by examining the success of previously published environment–recruitment correlations when tested with new data. The proportion of published correlations that have been verified upon retest is low. There is one generalization that stands out: correlations for populations at the limit of a species' geographical range have often remained statistically significant when re-examined. An examination of environment–recruitment correlations that were reviewed 13 years ago by Shepherd and co-workers shows that only 1 out of 47 reviewed studies is currently used in the estimation of recruitment in routine assessments. The results suggest that future progress will require testing general hypotheses using data from many populations.